As is well known in the art, integrated circuit (IC) chips are often subjected to rigorous testing to ensure their stability and usefulness. A number of sockets have been developed as carriers for the IC chips during testing procedures. Some of these prior sockets are shown in U.S. Pat. Nos. 4,491,877; 4,628,208; and 4,715,823, and in my U.S. patent application Ser. No. 667,470, filed Mar. 11, 1991.
The sockets described in each of the above documents all utilize flexible contacts which are shifted from a normally latched position into an unlatched position by movement of a spring biased top. In U.S. Pat. No. 4,491,377 the angled upper edge of the top cams against inner upper edges of the contacts to spread the contacts and allow for zero insertion force (ZIF) insertion and removal of the chip.
In U.S. Pat. Nos. 4,628,208 and 4,715,823, the flexible contacts include outer cantilevered ledges which are depressed by movement of the top to create a bending moment in the contact neck. This urges the contacts away from the chip to provide for the desired ZIF removal and insertion.
In my U.S. patent application Ser. No. 667,470, the top has angled abutment parts which contact the cantilevered ledges to evenly distribute and lessen the force required to spread the contacts. The ledges are also specially formed to facilitate the spreading function.
In all of the prior art devices described above, the contacts were positioned in the base so that when they were in their normal orientation, that is, unflexed, the contacts pressed against the chip leads (or the chip pods in the event a "leadless" chip was inserted) to both secure the chip in the socket and to provide electrical continuity during testing and burn-in procedures.